Catalytic alkylation process



Patented Sept. 3, 1946 CATALYTIC ALKYLATION PROCESS James B. Kirkpatrick, Woodbury, N. J., John J. Somers, Philadelphia, Pa., and Alexander N.

Sachanen,

Woodbury, N. J., assignors to Socony-Vacuum Oil Company, Incorporated, a

corporation of New York No Drawing. Application October 28, 1943, Serial No. 508,062

19 Claims. (Cl. 260683.4)

This invention relates to the alkylation of parafiinic hydrocarbons with olefinic hydrocarbons and is more particularly concerned with the production of high octane motor fuel by the catalytic alkylation of parafiinic hydrocarbons with olefinic hydrocarbons.

It is well known in the art to polymerize olefinic hydrocarbon gases to produce motor fuels having constituents of an unsaturated character. Various commercial processes have been proposed for ultimately effecting the desired polymerization of the olefinic hydrocarbons. These processes have been predicated upon the dictates of the chemical nature of the stocks available as well as engineering considerations such as initial and operation costs; their essential feature being that in the course of treating the materials, the olefinic hydrocarbons produced in the earlier stages of the process, are eventually polymerized to gasoline. Accordingly, hydrocarbon gases may be passed along with cracking stock or naphtha through a cracking still to crack and polymerize such gases to gasoline simultaneously with the cracking or reforming, or paraifinic hydrocarbon gases may be separately cracked to olefinic hydrocarbon gases and these gases are subsequently passed with naphtha through a polymerizing and reforming still. In some instances, the processes involve the use of catalysts for facilitatingthe cracking and/or polymerization operations.

It is also well known in the art, to combine paraffinic hydrocarbons directly with olefinic hydrocarbons by processes broadly called alkylation processes, to produce motor fuels having constituents of saturated character. In alkylation processes, a charge comprising a mixture oi a paraflinic hydrocarbon, called the paraflinic reactant, and an olefim'c hydrocarbon, called the olefinic reactant, is subjected to high temperature and pressure to produce a saturated alkylate product. Since conditions of alkylation also cause polymerization of the oleflnic reactant, it is necessary to maintain a relatively low concentration of the olefinic reactant in the charge. The only limit to the pressure used appears to be the feasibility of maintaining high pressures; On the other hand, the temperature used is limited by degradation of the hydrocarbon reactants in the charge to low molecular weight hydrocarbons, and the occurrence of side reactions, in-

cluding polymerization of the olefinic reactant- 2. atures and pressures, on the order of over 900 F. and over 4000 pounds per square inch gauge, respectively; or may be conducted in the presence of alkylation catalysts, at lower temperatures and pressures, thereby assuring a high yield of desired alkylate by avoiding extensive degradation of the reactants, the occurrence of side and secondary reactions, and appreciable polymerization of the olefinic reactant. The two methods are known as thermal alkylation and as catalytic alkylation, respectively. I

Several methods are known for the catalytic alkylation of isoparaffinic hydrocarbons with olefinic hydrocarbons. For instance, it is known to alkylate isoparafiinic hydrocarbons with olefinic hydrocarbons in the presence of sulfuric acid,

phosphoric acid, metal phosphates, metal halides, activated clays and the like, as catalysts. In these catalytic alkylation processes, the hydrocarbon reactants form with the alkylation catalysts, a heterogeneous system during the alkylation operation, Since under alkylation conditions, the catalytic activity of the alkylation catalysts appears to be predicated upon contact between the catalysts and the gaseous hydrocarbon reactants at the interfaces therebetween, in these processes, the catalysts are used in amounts varying between 10% and'200% by weight, on the charge, depending on the catalyst used. Due

to these comparatively high amounts, where posslble, recovery and regeneration of the catalyst have been proposed. This, of course, involves high initial and operation costs. Further, it is also known that certain substances called promoters, promote the catalytic action of these alkylation catalysts. Accordingly, several processes have been proposed wherein small amounts of these promoters, on the order of about 1% to 3% by weight on the charge, are added to the catalysts to promote their alkylation catalytic activity.

A copending application, Serial Number 502,018, filed September 11, 1943, in which one of the inventors of the present application is coinventor, is directed to the process of alkylating parafi'inic and isoparaflinic hydrocarbons with olefinic hydrocarbons, which comprises contacting a parafiinic or isoparafiinic hydrocarbon and an olefinic hydrocarbon in a reaction zone under alkylating conditions, with small or promotor amounts of what has been termed therein, a homogeneous gaseous phase alkylation catalyst consisting essentially of a material that forms with the hydrocarbon reactants, a single, homogeneous gaseous phase under the alkylation conditions of the reaction zone. The alkylation conditions of the process of this copending application, comprise a broad temperature range of about 590 F. to about 850 F., preferably, about 659 to about 825 F., and pressures or at least 500 pounds per square inch gauge, preferably, at least 1500 pounds per square inch gauge.

Another copending application, Serial Number 502,813, filed September 17, 19i3, is directed to the process of alkylating isobutane with propylene, which comprises contacting isobutane with propylene in a reaction zone under closely controlled alkylating conditions, with promoter or small amounts of the homogeneous gaseous phase catalysts broadly disclosed in the copending application referred to hereinabove, the closely controlled alkylating conditions including a team-- perature range of about 750 F. to about850 F., preferably, about 775 F. to about 825 F., and pressures of at least 2500 pounds per square inch gauge. In the alkylation of isobutane with propylene in the presence of homogeneous gaseous phase catalysts, it was found that the alkylate obtained included constituents that are entirely different from the constituents of the hydrocarbon alkylate obtained in the alkylation of isobutane with propylene in the presence of known heterogeneous alkylation catalysts, i. e.-, AlCls, H2304, and the like. Thus, when heterogeneous alkylation catalysts are used, 2,3-dimethylpentane and 2,4-dimethylpentane are important constituents of the hydrocarbon alkylate obtained. On the other hand, triptane or 2,2,3- trimethylbutane, 2,2-dimethylpentane, and 2- methylhexane are the predominant constituents of the hydrocarbon alkylate, when gaseous phase homogeneous alkylation catalysts are employed. In this copending application, the formation of these three compounds was postulated as follows:

Isobutane Propylene 2,2,3-trimethylbutane or triptane From a motor fuel standpoint, the 2,2-dimethylpentane produced by the first reaction, has an octane number of about 80 CF t motor method; the triptane produced by the second reaction has an octane number of well over 100, and the Z-methylhexane obtained in the third reaction, has an octane number of about 45. In View of the foregoing, in the manufacture of high octane motor fuel by the alkylation of isobutane' with propylene, alkylation conditions that favor the production of triptane obviously are preferable. Further, since neohexane which may be produced by the alkylation of isobutane with ethylene, has an octane number of 93.4, and since- 2,3-dimethylpentane' and; 2', l-dimethylpentane which are the predominant constituents of the alkylate obtained in the alkylation of isobutane with propylene in the presence of heterogeneous alkylation catalysts, have octane numbers of 89 and 82, respectively, the importance of the alkylation of isobutane with propylene in the presence of homogeneous gaseous phase catalysts under alkylation conditions that favor as production of triptane is manifest. It was also found that in actual practice, it was impossible to obtain triptane exclusively, appreciable amounts of 2,2-dimethylpentane 2-methylhexane being always formed.

The specific classes of homogeneous gas-ecu phase catalysts claimed in the above-noted co bromides.

We have found that organic compounds are suitable homogeneous gaseous phase allzyla tion catalysts and that isopar affi'nic hydrocarbons may be effic :15 a with olefinic hydrocarbons to produce high yields of high octane gasoline by using small or promoter amounts of organic nitro compounds form with the hydrocarbon reactants, a single, homogeneous gaseous phase during the alkylation operation.

-We have also found that organic nitro com pounds are suitable homogeneous gaseous phase catalysts in the catalytic alkylation of sobntane with propylene under the controlled condition" of alkylation described in the copending ap tion, Serial Number 502,813, filed September 1'7, 1943.

It is an object of the present invention toprovide an efiicient process for cataiytically alhylab ing isoparafiinic o-r parafiinic hydrocarbons with olefinic hydrocarbons. Another object of the present invention is to provide an efiicient process for catalytically alkylating either normal paraffinic hydrocarbons or isoparafiinic hydrocarbons with olefinic hydrocarbons to produce high yields of highoctane gasoline. A more spe object is to provide a process for catalyticaiiy alkylating isobutane with propylene to produce high-yields of high octane gasoline. A very important 'object of the present invention is to aiTord a process capable of carrying out the above objects by using small or promoter amounts of organicnitro compounds that form with the hydrocarbon reactants, a single, homogeneous gaseous phase during the alkylation operation. Qther objects and advantages of the present iiivention Will become apparent to those skilled in the art from the following description.

Broadly stated, our invention provides a process forialkylating normal paraffinic or isoparaflinic hydrocarbons, particularly isobutane, with olefinic hydrocarbons, such as ethylene, propylene, and butylenes which comprises contacting the parafiinic and olefinic hydrocarbons in gaseous phase and in a reaction zone under alkylating conditions, with small or promoter amounts of an alkylation catalyst consisting essentially of organic nitro compounds, particularly nitro methane, that forms with the hydrocarbon reactants, a 'singlehomogeneous gaseous phase under the alkylation conditions of the reaction zone.

An important feature of the process of the present invention is the fact that, contrary to the known catalytic alkylation processes of the prior'ar't which are only capable of alkylating isoparaflinic hydrocarbons, our process is capable ofalkylatingeither normal parafiinic or isoparr propane. 1

afiinic, hY QI'QQaIbODSQ with Substantially equal ease.-, t.

Another important vfeature of, the process of the present invention is .the relativelyrlow temperature that may be used. .As a result, degradation of the hydrocarbon reactants in the charge to low molecular weight hydrocarbons and'the pro nounced occurrence of side reactions including polymerization of the oleiinic hydrocarbons, are substantially completely avoided. Consequently, in our process, we obtain highfyields of a hig grade'product'that is almost entirely paraliinic innature and issubstantially free from impurities. a 1 I \r A very important feature ofthe present invention is the fact that, contrary to known catalytic processes of the prior art 1n-Whlch the hy-- drocarbon reactants beingprocessed form with the alkylation catalysts, aheterogeneous system during the alkylation operation, the alkylation process of our invention employs alkylation catalysts consisting essentially of materials that form a with the hydrocarbon reactants being processed, a single, homogeneous gaseous phase under alKylating conditions. The alkylation catalysts f the present invention may be called, therefore, homogeneous gaseous phase catalysts in contradistinction to the alkylation catalysts of the prior art winch may be referred to as heterogeneous catalysts. fAcco'rdingly, as a result of thecatalysts being in the same phase or state as the hydrocarbon reactants being processed, fouling of the catalyst'is substantially elimmated and agitation and/or mixing problems are non-extant. liurther, since the catalytic activity of allrylation catalysts appears to be predicated somewhat upon contact between the catalysts and the gaseous hydrocarbon reactants at the interfaces therebetween, it follows that the catalytic eniciency of a given catalyst increases with the increase in area of interfacial contact, other variables remaining constant. Hence, since the homogeneous catalysts or our process inherently furnish the greatest possible interracial contact between the catalyst and the hydrocarbon reactants under the conditions of-alkylation, eflicient catalytic activity with a concomitant high yield of high grade alkylate is achieved using relatively small amounts of homogeneous gaseous phase catalyst.

In View of the foregoing, an operation feature of the process of the present invention that is of considerable practical importance is that small or promoter amounts of organic nitro compounds 7 are used as alkylation catalysts. These amounts are so small that they may be discarded feasibly, thereby obviating recovery and regeneration problems and eliminating high initial and operation costs. V

A' most important feature of the present invention is that high yields of high octane motor fuel are obtained by alkylating' isobutane with propylene in the presence of organic nitro compounds, particularly, nitro methane and nitro 'As disclosed in application Serial l lumber 502,018, filed September 11,1943, the homogeneous gaseous phase alkylation catalysts of" the present invention'may be solids, liquids or gases under normal conditions. However, it is likewise essen-. tial for the purposes of our process, that the organic nitro compounds form with the hydrocarbon reactants being processed, a, single, homo- I geneous gaseous phase under, the alkylatiorla'conditionsgpf the process. Generally 'speaking, the;

of hydrocarbons wherein the nitro group is substituted onto anon-ring portion, if any, of the hydrocarbons. It is to be understood, herein, that by nitro derivatives of hydrocarbons, we mean compounds wherein all the. hydrogen has been substituted by the nitro group, or compounds wherein only partof the hydrogen has been substituted, as well as compounds wherein part, of theuhydrogen'hasr been substituted by thenitro group and part of the hydrogen has been. substituted by halogens, particularly chlorine and bromine. We especially prefer touse as .our ,homogeneous gaseous. phase alkylation catalysts, nitro ..d'erivatives of light paraffinie hy-, drocarbons, in view of their volatility at moderate temperatures. Thus,at the present time, we consider rnitromethane, nitropropane, 1.-nitro-'-1- chloropropane, and nitrobenzyl typical examples of .the homogeneous gaseous phase alkylation catalysts ofour invention. It is to be understood,

of course, that the homogeneous gaseous phase alkylation catalystsof 'our invention, may be formed in: situ. This may be done by injecting thelproper amount of nitric acid into the mixture to be treated. Under the temperatures used in our process, aliphatic hydrocarbons of low molecular weight will be nitrated to produce the catalysts of our invention.

The amount oforganic nitro compounds used in our process, varies between about 0.5% and about 3%, and preferably, between about 1% and about 1.25%, with respect to the total charge of hydrocarbon reactants. It must be noted, however, that larger amounts of organic nitro compounds may-be employed if desired, although no additional advantages result therefrom.

The paraflinic and olefinic hydrocarbons to be used in our process may be derived from any suitable'source, as is well known in the art, and may be used either in the pure state or in'admixture with other constituents not undesirable. The 45 paraffinic and olefinic hydrocarbons usually employed in the preferred operation of manufacturing motor fuels will be the normally gaseous paraflinic hydrocarbons, except methane and ethane, and the normally gaseous olefinic hydrocarbons, 50 as is well understood in the art. Here again our process has a distinct advantage over many of the prior art processes in that the olefin ethylene may be used for alkylating the parafiinic hydrocarbons. It is well known that ethylene cannot be '55 used in many catalytic processes, including the sulfuric acid process, whereby the supply of available olefinic hydrocarbons is restricted. Therefore, an important aspect of the present invention is the fact that butane, for instance, may bealkylated with ethylene. r

A'conventional and preferred source of paraffinic and olefinic hydrocarbons is the fixed gases obtained around petroleum refineries. These fixed gases may furnish substantially all the de- '65 sired paraffinic and olefinic hydrocarbons, or it maybe necessary or desirable to obtain additional supplies, as is well understood. Additional olefinic hydrocarbons, if required, may be formed carbons may be admixed to increase theconcenmagnitude. v

N V In-' carrying} out our I process, we a use tempera-"i turesiva'rying between about 590? andabout frorn'a portionof the parafiinic hydrocarbons: 7 On the other hand, additional parafiinic hydro- 7 850? R, and preferably temperatures varying between about 650 F. and about 825- F. In the alkylation of isobutane with propylene, howeverywe have found, as disclosed in the copending application Serial Number 502,813, filed September 17, 1943, that the best yields of desired alkylate are obtained when the alkylation is conducted at temperatures falling within about 750" F. :to about 850 F., and preferably, about 775 F. to about 825 F. .The allzylate produced under these conditions contains nomore than of olefinic hydrocarbons. and no aromatics so that the predominance of alkylation obtainedthereby is a distinct feature of. the process. Under appreciably higher temperature conditions,- side reactions occur that substantially. reduce thepurity of theproduct obtained. In the alkylation. of isobutane with pro pylene in accordance with the process of the present. invention, itmust be noted that even within the.-,.preferred temperature range, side reactions occurthat account for substantial portions. ofthe total alkylate, but a fraction boilingat'IQF C. to

82 C. andconsistingof. l5'parts of triptane to 85 partsof 2,2-di1nethylpentane may be obtained.

The pressure to be used in our process may vary from about 500 pounds per square inch to about 6000 pounds per square inch or more, and preferably, from about 2500 pounds-per square inch, to about 6000 pounds per. square ,inch for the allrylation of isobutane with propylene, the most suitable pressure being. more or less dependent upon the particular temperature involved. In general, the higher the pressure, the higher the yield of alkylate. Accordingly, the criterion for establishing an upper limit to the pressure range used is primarily the, feasibility of maintaining such pressure.

In our process it is desirable, as in known iso-. paraffin-olefin alkylation processes, to keep the concentration of the olefinic hydrocarbons relatively low during the alkylation reaction in order to eliminate as much olefin polymerization as possible. Accordingly, it is advisable to maintain the olefin concentration in the charge below about 25% by volume, and preferably between about 7% and about 12% by volume.

The alkylate product that We obtain distills over a fairly large boiling range, but a greater part of the alkylate, usually from about 85% to about 90%, distills in the boiling range of aviation gasolines. The iodine number of the aviation distillate is low, on the order of about 5 to 10. As mentioned hereinabove, the alkylate product consists predominantly of branched paraflinic hydrocarbons.

. Example 1 Commercial butane was alkylated with ethylene in a bomb at 700 F., under a pressure of 3200 pounds per square inch, for 30 minutes, non-catalytically and catalytically in the presence of 1.2%

by weighton the charge, of nitromethane. The

results were as follows:

The results show that the catalytic process forms a much greater yield of reaction product,

. 8 uct. obtained when the alkylation is carried out in the presence of nitromethane, is highly parafiinic, i. e., his the result of alkylation, whereas the product-of the non-catalytic process is highly olefinic, i. e.,,it is the result of polymerization.

" Ewam zez rs'obutane. tasaizyjl'asayaa propylene in a continuous operation, in a pipe still at 775. F. to

890 .F. andunder a..pressure of 6000 pounds per square inch...$i x and a hal inches of isobutane per one moleoitmnr pe were employed. The process was. carriedout non catalytically, and catalytically in the presence of 1.2% by weight on the charge of nitromethane. Theresults were as ol ows;

ymn or I r i alkylate sgf g Iodine numl a with r spect lkylatei berqfg-lkyhte 5 D l boiling up "g i fi 1,?

percen'oy l v o to 400s r.

None ro 0; 760 n Nitromethana 97.0 0.70 g

' The results show as in Example 1, that" the catalytic process forms a much "greater yield of reaction product which is substantially paraffinic, whereas'the non-catalytic process forms a prodnet-with high olennic content; "In addition, the narrow fraction of the alkylate boiling'between 79 C. and 82 0;, showed the presence of'15% triptane in the catalytic allrylate, whereas this hydrocarbon was substantially absent'in the same fraction in the non-catalytic product.

Althoughthe present invention has been 'described. in'conjunction with preferred embodiments-ii; is to-be understood that modifications and-variations may be resorted to without departing from the spirit and scope of the invention; as those-skilled in the artwill readily understand. Such variations and modifications are considered to be within the purview and scope of the append ed claims.

We. claim: a a 1. In a process of manufacturing triptane by alkylating isobutane with propylene'in a reaction zone under alkylating conditions and in the presence oiv catalytic material; the improvement which comprises contacting said isobutane and said propylene in said reaction zone under alkylating conditions including a temperature varying between about 775 F. and about 825 F. and a pressure of at least 25.00.pounds per square inch, with an alkylation catalyst consisting essentially of nitromethane, in amountsv varying between about 1% and about 1.25% of the charge, and controlling the concentration of the propylene so that alkylation is the principal reaction. 1

V 2 The process of manufacturing high-octane gasoline which comprises contacting a light paraffinic hydrocarbon and a light olefinic hydrocarbon in a reaction zone under alkylating conditions including. a temperature varying between about 650 F. and about 825 F. and a pressure of at least 1500 pounds per square inch, with an alkylation catalyst consisting essentially of nitro-. methane, and controlling the concentration of the light olefinic reactant so that alkylation is the principal reaction. v 3. The process of claim 2 wherein the alkylation-catalyst consists essentially of 1-nitro-1- chloropropane. a

,4. .The process of-a1kylating isobutane with Further, theiodine numbers show that theprod-; propylenewhich comprises contacting said isobutane and said propylene in a reaction zone under alkylating conditions, including a temperature varying between about 750 Rand about 850 F. and a pressure of at least 2500 pounds per square inch, with an alkylation catalyst consisting essentially of nitromethane, and controlling the concentration of the propylene so that alkylation is the principal reaction.

5. The process of claim 4 wherein the alkylation catalyst consists essentially of l-nitro-lchloropropane.

6. In a process of manufacturing high-octane gasoline by alkylating isobutane with propylene in a reaction zone under alkylating conditions and in the presence of catalytic material; the improvement which comprises contacting said isobutane and said propylene in said reaction zone under alkylating conditions including a temperature varying between about 775 F. and about 825 F. and a pressure of at least 2500 pounds per square inch, with an alkylation catalyst consisting essentially of nitromethane, and controlling the concentration of the propylene so that alkylation is the principalreaction.

7. The process of alkylating a paraflinic hydrocarbon with an olefinic hydrocarbon, which comprises contacting said parafiinic hydrocarbon and said olefinic hydrocarbon in a reaction zone under alkylating conditions including a temperature varying between about 590 F. and about 850 F. and a pressure of at least 500 pounds per square inch, with an alkylation catalyst consisting essentially of nitromethane, and controlling the concentration of the olefinic reactant so that alkylation is the principal reaction.

8. In a process of manufacturing triptane by alkylating isobutane with propylene in a reaction zone under alkylating conditions and in the presence of catalytic material; the improvement which comprises contacting said isobutane and said propylene in gaseous phase and in said reaction zone under alkylating conditions including a temperature varying between about 775 F. and 825 F. and a pressure of at least 2500 pounds per square inch. with an alkylation catalyst consisting essentially of a nitro derivative of a light paraflinic hydrocarbon which forms with said isobutane and said propylene. a single, homogeneous gaseous phase under said alkylating conditions, in amounts varying between about 1% and about 1.25% of the charge, and controlling the concentration of the propylene so that alkylation is the princ al reaction.

9. The process of alk lating a light paraffinic hydrocarbon with a li ht olefinic hydrocarbon, whichcomnrises contacting sa d light paraflinic hydrocarbon and said light olefinic hydrocarbon in gaseous phase and in a reaction zone under alkylating conditions including a temperature varying between about 590 F. and about 850 F. and a pressure of at least 500 ounds per souare inch. with an alkylation" catalyst consisting essentiallv of an organic nitro compound which forms with sa d light paraifinic hydrocarbon and said l ght olefinic hydrocarbon. a single, homogeneous gaseous phase under said alkylation conditions. and controlling the concentration of the light olefinic reactant so thatalkylation is the principal reaction.

10. The process of claim 9 wherein the alkylation catalyst consists essentially of a nitro derivative of a light paraffinic hydrocarbon.

11. In a process of alkylating isobutane with propylene in a reaction zon under alkylating conditions and in the presence of catalytic material; the improvement which comprises contacting said isobutane and said propylene in gaseousphase and in said reaction zone under alkylating conditions including a temperature varying between about 750 F. and about 850 F. and a pressure of at least 2500 pounds per square inch,

with an alkylationcatalyst consisting essentially of an organic nitro compound which forms with said isobutane and said propylene, a single, homogeneous gaseous phase under said alkylating conditions, and controlling the concentration of the propylene so that alkylation is the rincipal reaction.

12. The process of claim 11 wherein the alkylation catalyst consists essentially of a nitro derivative of a light paraffinic hydrocarbon.

13. In a process of manufacturing high-octane gasoline by alkylating a light paraifinic hydrocarbon with a light olefinic hydrocarbon in a reaction zone under alkylating conditions and in the presence of catalytic material; the improvement which comprises contacting said light parafiinic hydrocarbon and said light olefinic hydrocarbon in gaseous phase and in said reaction zone under alkylating conditions including a temperature varying between about 650 F. and about 825 F. and a pressure of at least 1500 pounds per square inch, with an alkylation catalyst consisting essentially of an organic nitro compound which forms with said light paraflinic hydrocarbon and said light olefinic hydrocarbon, a single, homogeneous gaseous phase under said alkylating conditions, and controlling the concentration of the light olefinic reactant so that alkylation is the principal reaction.

14. The process of claim.13 wherein the alkylation catalyst consists essentially of a nitro derivative of a light paraflinic hydrocarbon.

15. The process of manufacturing high-octane gasoline, which comprises contacting isobutane and propylene in gaseous phase and in a reaction zone under alkylating conditions including a temperature varying between about 775 F, and about 825 F. and a pressure of at least 2500 5 pounds per square inch, with an alkylation catalyst consisting essentially of an organic nitro compound which forms with said isobutane and said propylene, a single, homogeneous gaseous phase under said alkylation conditions, and con- 50 trolling the concentration of the propylene so that alkylation is the principal reaction.

16. The process of claim 15 wherein the alkylation catalyst consists essentially of a nitro derivative of a light paraffinic hydrocarbon.

17. The process of manufacturing triptane which comprises contacting isobutane and propylene in gaseous phase and in a reaction zone under alkylating conditions including a temperature varying between about 775 F. and about 825 F. and a pressure of at least 2500 pounds per square inch, with an alkylation catalyst consisting essentially of an organic nitro compound which forms with said isobutane and said propylene, a single, homogeneous gaseous phase under said alkylation conditions, in amounts varying between about 0.5% and about 8% of the charge, and controlling the concentration of the propylene so that alkylation is the principal re action.

18. In a process of alkylating a paraffinic hydrocarbon with an olefinic hydrocarbon in a reaction zone under alkylating conditions and in the presence of catalytic material; the improvement which comprises contacting said paraflinic hydrocarbon and said olefinic hydrocarbon in carbon and aid olefinic hydrocarbon, a single, H

homogeneous gaseous phase under said alkylatin conditions, and controlling the concentration of the olefinic reactant so that alkylation is the principal reaction.

12 19. The process of claim 18 wherein the alkylation catalyst consists essentially of a nitro derivative of a light parafiinic hydrocarbon.

JAMES B. KIRKPATRICK. JOHN J. SOMERS. ALEXANDER N. SACI-IANEN. 

